In many technical areas, mainly in the installation technology, problems arise after the laying of pipes, especially in case of bends or non-lineal laying, if a swiveling of the pipes cannot be avoided due to e.g. external influences. A special example for such external influences on pipes which are usually laid in a straight manner, can be seen in underground mining, i.e. tube-type pressure pipes in the mining equipment. By moving the mining equipment forward from section to section, the pipe is turned in such a way that the connections become permanently leaky and damaged. A comparable problem arises in the case of smaller bending radii, especially high-pressure hoses, which are permanently leaky and damaged. A comparable problem arises in the case of smaller bending radii, especially high-pressure hoses, which are permanently moved or turned.
So called ball-headed connections are used and as they are described--among others in DE-OS 26 31 984 and in DE-AS 10 75 907.
The main disadvantage of such ball-head connections is, on the one hand, the limited angle which can be formed and, on the other hand, the fixing of the union nut which leads to a stiffening of the connection. The stiffening of such a connection finally results in the same problems for both pipes being moved by external influences and pipes laid in a straight and rigid manner. As not only the firmness of such connections is of great importance, but also the tensile strength--especially in case of higher pressures--and the connection does not create enough contact retention, their use is extremely limited, not only because of the lower swivelability and the rigidity.
Furthermore, there is a ball-shaped joint-connection in use, as is described in detail in DE-OS 16 50 030, which mainly aims at the special problems of sealing and movability under pressure. The potential solution might be that there are further internal surface-parts at the bell tap and at the ball pan and/or the pan nut of the floated medium parallel to the direction of flow, which mainly face the corresponding first internal surface parts.
Apart from the fact that such a ball-bead tube connection mainly requires great technical efforts in the single components, it is very complicated, large-volume and has the disadvantage that the flow medium causes enormous turbulences in each position of the connection. Due to design reasons, the sealing-off requires a variety of sealings with recesses and sealing-rings, which inevitably leads to the movement being impaired by stress.